<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>盒子模型</title>
</head>
<style>
    .one {
        width: 200px;
        height: 200px;
        border: 10px solid #333;
        box-sizing: border-box;
    }
    .two {
        width: 200px;
        height: 200px;
        border: 10px solid #333;
        /* 内容盒子是默认值，也就是浏览器默认采用这种盒子渲染元素 */
        box-sizing: content-box;
    }
</style>
<body>
    <div class="one"></div>
    <div class="two"></div>
</body>
</html>